Laser Impurity Activation in Group III Nitride Field Effect Transistors
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Solution Overview
Problem
Conventional high-temperature annealing methods for activating impurities in group III nitride semiconductor materials lead to substrate damage, Ga droplet formation, nitrogen desorption, and crystalline defects, resulting in reduced channel mobility and reliability issues in field effect transistors.
Innovation Solution
A method involving the irradiation of a laser beam with energy higher than the band gap energy of the semiconductor material to activate impurities, eliminating the need for high-temperature substrate heating and using a protective film with lower band gap energy to prevent unnecessary heating of non-implanted regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature annealing treatment is applied to activate impurities, then impurity activation is achieved, but substrate damage and crystalline defects occur
Solution Approach 1:
The patent changes the activation method from thermal annealing to laser beam irradiation, fundamentally altering the physical parameter used for impurity activation. The laser beam with energy higher than the band gap energy directly activates impurities through photoexcitation rather than thermal energy, avoiding the substrate damage associated with high temperature treatment
Solution Approach 2:
The patent replaces the thermal field (heat-based annealing) with an optical field (laser beam irradiation). This substitution eliminates the need for high temperature heating while achieving the same impurity activation effect, thereby preventing substrate damage and crystalline defects
2Reliability
If high temperature annealing treatment is applied to activate impurities, then impurity activation is achieved, but Ga droplet formation and nitrogen desorption occur
Solution Approach 1:
The patent changes the activation method from thermal annealing to laser beam irradiation, fundamentally altering the physical parameter used for impurity activation. The laser beam with energy higher than the band gap energy directly activates impurities through photoexcitation rather than thermal energy, avoiding the Ga droplet formation and nitrogen desorption associated with high temperature treatment
Solution Approach 2:
The patent replaces the thermal field (heat-based annealing) with an optical field (laser beam irradiation). This substitution eliminates the need for high temperature heating while achieving the same impurity activation effect, thereby preventing Ga droplet formation and nitrogen desorption
3Reliability
If high temperature annealing treatment is applied to activate impurities, then impurity activation is achieved, but channel mobility is reduced
Solution Approach 1:
The patent changes the activation method from thermal annealing to laser beam irradiation, fundamentally altering the physical parameter used for impurity activation. The laser beam with energy higher than the band gap energy directly activates impurities through photoexcitation rather than thermal energy, avoiding the crystalline defects that reduce channel mobility
Solution Approach 2:
The patent replaces the thermal field (heat-based annealing) with an optical field (laser beam irradiation). This substitution eliminates the need for high temperature heating while achieving the same impurity activation effect, thereby maintaining channel mobility without crystalline defects
4Object-affected harmful factors
If laser beam with higher energy than band gap energy is irradiated, then impurities are activated without substrate damage, but protective film is required to prevent overheating of non-implanted regions
Solution Approach 1:
The patent applies local quality by forming a protective film only in specific regions where impurities are not implanted. This selective film formation prevents laser-induced overheating in non-implanted regions while allowing direct laser activation in implanted regions, balancing protection needs with activation efficiency
Solution Approach 2:
The protective film acts as an intermediary layer that modulates the laser beam interaction with the semiconductor substrate. It prevents excessive energy absorption and overheating in non-implanted regions while allowing the laser to effectively activate impurities in implanted regions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively activates impurities without deteriorating device performance or reliability, preventing Ga segregation, nitrogen desorption, and crystalline defects, thus maintaining high carrier mobility and breakdown voltage in field effect transistors.
Implementation Method 1
irradiating a laser beam having a higher energy than a band gap energy of the material forming the carrier moving layer
Implementation Method 2
laser beam with a wavelength having a higher energy than the band gap energy of the material forming the carrier moving layer is irradiated
Data Source
AI summary
The laser beam with a wavelength having a higher energy than the band gap energy of the material forming the carrier moving layer is irradiated to activate the impurities contained in the constituent layer of the field effect transistor in the method of producing the field effect transistor. The method of the invention does not apply the heating of the substrate or the sample stage to raise the temperature of the semiconductor layer using the thermal conductivity so as to activate the impurities. Thus, the implanted impurities can be activated without deteriorating the performance of the device and reliability.